Various vaccines against serogroup B of Neisseria meningitidis (“MenB”) are currently being investigated. Some of these are based on outer membrane vesicles (OMVs), such as the Novartis MENZB™ product, the Finlay Institute VA-MENGOC-BCT™ product, and the Norwegian Institute of Public Health MENBVAC™ product. Reference 1 discloses the construction of vesicles from strains modified to express six different PorA subtypes. References 2-4 report pre-clinical studies of an OMV vaccine in which fHbp (also known as GN1870) is over-expressed (and this over-expression can be combined with knockout of LpxL1 [5]). Reference 6 recently reported a clinical study of five formulations of an OMV vaccine in which PorA & FrpB are knocked-out and Hsf & TbpA are over-expressed. Reference 7 reports a native outer membrane vesicle vaccine prepared from bacteria having inactivated synX, lpxL1, and lgtA genes.
It is an object of the invention to provide further and improved meningococcal OMVs, and also to provide further and improved meningococci for use in vaccine production.